This invention relates to tubeless tires and, more particularly, to tires of the radial-carcass type having improved new or recapped treads and intended to be used on vehicles of the truck class.
Truck tires of the radial type are generally provided with treads cut into circumferential ribs by means of grooves, generally but not necessarily four in number, extending over the entire periphery of the tread.
This type of molding leads, under certain circumstances, and particularly as a result of prolonged travel on highways, to a special form of wear: superimposed on the grooves there are formed two troughs that are wider but shallower than the grooves. In order to eliminate this form of wear, it has previously been proposed to cut the edges of the longitudinal ribs transversely by means of fine cuts of small length spaced closely from each other so as to make the side portions of the ribs more flexible than the central portions.
This means has proven effective and of great value; however, when it is sought to improve the effectiveness of the cuts still further, particularly by increasing their length, in order to increase the flexibility of the lateral portions of the ribs, the overall improvement is not as great as one might desire. An additional reduction in the characteristic wear described above has been noted, as a matter of fact, but in addition there has been observed the appearance of another special form of wear, this time affecting the longitudinal profile of the cut circumferential ribs--they assume a sawtooth shape.